ImageDev

SnnFilter2d

Performs an edge-preserving smoothing of a two-dimensional image with the Symmetric Nearest Neighbor filter.

Access to parameter description

For an introduction to image filters: see Images Filtering.

This algorithm implements the Symmetric Nearest Neighbor filter (SNN), which is an average filter weighted by the structural symmetry of a rectangular neighborhood window. It computes a local mean around a central pixel $x$, considering for each neighbor pixel $y$, having a gray level $I(y)$, the value given by:
$$ I'(y)=\left\{\begin{array}{ll} I(y) & ~\mbox{if $|I(x)-I(y)| < |I(x)-I(y_s)|$} \\ I(y_s) & ~\mbox{if $|I(x)-I(y)| > |I(x)-I(y_s)|$} \\ I(x) & ~\mbox{otherwise} \end{array}\right. $$ Where $y_s$ is the neighbor pixel symmetric to $y$ with respect to $x$.

The output value of the pixel $x$ is then given by: $$ O(x)=\mu[I'(y)] $$ Where $\mu$ is the mean value of the local window.

See also

Function Syntax

This function returns the outputImage output parameter. 
// Function prototype.
std::shared_ptr< iolink::ImageView >
snnFilter2d( std::shared_ptr< iolink::ImageView > inputImage,
             int32_t kernelSizeX,
             int32_t kernelSizeY,
             std::shared_ptr< iolink::ImageView > outputImage = NULL );
This function returns the outputImage output parameter. 
// Function prototype.
snn_filter_2d( input_image,
               kernel_size_x = 3,
               kernel_size_y = 3,
               output_image = None )
This function returns the outputImage output parameter. 
// Function prototype.
public static IOLink.ImageView
SnnFilter2d( IOLink.ImageView inputImage,
             Int32 kernelSizeX = 3,
             Int32 kernelSizeY = 3,
             IOLink.ImageView outputImage = null );

Class Syntax

Parameters

Class Name SnnFilter2d

Parameter Name Description Type Supported Values Default Value
input
inputImage
The input image. Image Binary, Label, Grayscale or Multispectral nullptr
input
kernelSizeX
The horizontal kernel size in pixels (odd value). Int32 [3, 100] 3
input
kernelSizeY
The vertical kernel size in pixels (odd value). Int32 [3, 100] 3
output
outputImage
The output image. Its dimensions, type and calibration are forced to the same values as the input. Image nullptr

Object Examples

std::shared_ptr< iolink::ImageView > polystyrene = ioformat::readImage( std::string( IMAGEDEVDATA_IMAGES_FOLDER ) + "polystyrene.tif" );

SnnFilter2d snnFilter2dAlgo;
snnFilter2dAlgo.setInputImage( polystyrene );
snnFilter2dAlgo.setKernelSizeX( 3 );
snnFilter2dAlgo.setKernelSizeY( 3 );
snnFilter2dAlgo.execute();

std::cout << "outputImage:" << snnFilter2dAlgo.outputImage()->toString();

polystyrene = ioformat.read_image(imagedev_data.get_image_path("polystyrene.tif"))

snn_filter_2d_algo = imagedev.SnnFilter2d()
snn_filter_2d_algo.input_image = polystyrene
snn_filter_2d_algo.kernel_size_x = 3
snn_filter_2d_algo.kernel_size_y = 3
snn_filter_2d_algo.execute()

print( "output_image:", str( snn_filter_2d_algo.output_image ) );

ImageView polystyrene = ViewIO.ReadImage( @"Data/images/polystyrene.tif" );

SnnFilter2d snnFilter2dAlgo = new SnnFilter2d
{
    inputImage = polystyrene,
    kernelSizeX = 3,
    kernelSizeY = 3
};
snnFilter2dAlgo.Execute();

Console.WriteLine( "outputImage:" + snnFilter2dAlgo.outputImage.ToString() );

Function Examples

std::shared_ptr< iolink::ImageView > polystyrene = ioformat::readImage( std::string( IMAGEDEVDATA_IMAGES_FOLDER ) + "polystyrene.tif" );

auto result = snnFilter2d( polystyrene, 3, 3 );

std::cout << "outputImage:" << result->toString();

polystyrene = ioformat.read_image(imagedev_data.get_image_path("polystyrene.tif"))

result = imagedev.snn_filter_2d( polystyrene, 3, 3 )

print( "output_image:", str( result ) );

ImageView polystyrene = ViewIO.ReadImage( @"Data/images/polystyrene.tif" );

IOLink.ImageView result = Processing.SnnFilter2d( polystyrene, 3, 3 );

Console.WriteLine( "outputImage:" + result.ToString() );